package spider.util;
/**

 Porter stemmer in Java. The original paper is in

 Porter, 1980, An algorithm for suffix stripping, Program, Vol. 14,
 no. 3, pp 130-137,

 See also http://www.tartarus.org/~martin/PorterStemmer

 History:

 Release 1

 Bug 1 (reported by Gonzalo Parra 16/10/99) fixed as marked below.
 The words 'aed', 'eed', 'oed' leave k at 'a' for step 3, and b[k-1]
 is then out outside the bounds of b.

 Release 2

 Similarly,

 Bug 2 (reported by Steve Dyrdahl 22/2/00) fixed as marked below.
 'ion' by itself leaves j = -1 in the test for 'ion' in step 5, and
 b[j] is then outside the bounds of b.

 Release 3

 Considerably revised 4/9/00 in the light of many helpful suggestions
 from Brian Goetz of Quiotix Corporation (brian@quiotix.com).

 Release 4

 */

import java.util.regex.Pattern;

/**
 * Stemmer, implementing the Porter Stemming Algorithm
 * <p/>
 * The Stemmer class transforms a word into its root form.  The input
 * word can be provided a character at time (by calling add()), or at once
 * by calling one of the various stem(something) methods.
 */

public class Stemmer {
    private char[] b;
    private int i, /* offset into b */
            i_end, /* offset to end of stemmed word */
            j, k;
    private static final int INC = 50;

    /* unit of size whereby b is increased */
    public Stemmer() {
        b = new char[INC];
        i = 0;
        i_end = 0;
    }

    private void reset() {
        b = new char[INC];
        i = 0;
        i_end = 0;
    }

    /**
     * Add a character to the word being stemmed.  When you are finished
     * adding characters, you can call stem(void) to stem the word.
     */

    public void add(char ch) {
        if (i == b.length) {
            char[] new_b = new char[i + INC];
            System.arraycopy(b, 0, new_b, 0, i);
            b = new_b;
        }
        b[i++] = ch;
    }

    /**
     * Adds wLen characters to the word being stemmed contained in a portion
     * of a char[] array. This is like repeated calls of add(char ch), but
     * faster.
     */

    public void add(char[] w, int wLen) {
        if (i + wLen >= b.length) {
            char[] new_b = new char[i + wLen + INC];
            System.arraycopy(b, 0, new_b, 0, i);
            b = new_b;
        }
        for (int c = 0; c < wLen; c++)
            b[i++] = w[c];
    }

    /**
     * After a word has been stemmed, it can be retrieved by toString(),
     * or a reference to the internal buffer can be retrieved by getResultBuffer
     * and getResultLength (which is generally more efficient.)
     */
    public String toString() {
        return new String(b, 0, i_end);
    }

    /**
     * Returns the length of the word resulting from the stemming process.
     */
    public int getResultLength() {
        return i_end;
    }

    /**
     * Returns a reference to a character buffer containing the results of
     * the stemming process.  You also need to consult getResultLength()
     * to determine the length of the result.
     */
    public char[] getResultBuffer() {
        return b;
    }

    /* cons(i) is true <=> b[i] is a consonant. */

    private final boolean cons(int i) {
        switch (b[i]) {
            case'a':
            case'e':
            case'i':
            case'o':
            case'u':
                return false;
            case'y':
                return (i == 0) || !cons(i - 1);
            default:
                return true;
        }
    }

    /* m() measures the number of consonant sequences between 0 and j. if c is
        a consonant sequence and v a vowel sequence, and <..> indicates arbitrary
        presence,

           <c><v>       gives 0
           <c>vc<v>     gives 1
           <c>vcvc<v>   gives 2
           <c>vcvcvc<v> gives 3
           ....
     */

    private final int m() {
        int n = 0;
        int i = 0;
        while (true) {
            if (i > j)
                return n;
            if (!cons(i))
                break;
            i++;
        }
        i++;
        while (true) {
            while (true) {
                if (i > j)
                    return n;
                if (cons(i))
                    break;
                i++;
            }
            i++;
            n++;
            while (true) {
                if (i > j)
                    return n;
                if (!cons(i))
                    break;
                i++;
            }
            i++;
        }
    }

    /* vowelinstem() is true <=> 0,...j contains a vowel */

    private final boolean vowelinstem() {
        int i;
        for (i = 0; i <= j; i++)
            if (!cons(i))
                return true;
        return false;
    }

    /* doublec(j) is true <=> j,(j-1) contain a double consonant. */

    private final boolean doublec(int j) {
        if (j < 1)
            return false;
        if (b[j] != b[j - 1])
            return false;
        return cons(j);
    }

    /* cvc(i) is true <=> i-2,i-1,i has the form consonant - vowel - consonant
        and also if the second c is not w,x or y. this is used when trying to
        restore an e at the end of a short word. e.g.

           cav(e), lov(e), hop(e), crim(e), but
           snow, box, tray.

     */

    private final boolean cvc(int i) {
        if (i < 2 || !cons(i) || cons(i - 1) || !cons(i - 2))
            return false;
        {
            int ch = b[i];
            if (ch == 'w' || ch == 'x' || ch == 'y')
                return false;
        }
        return true;
    }

    private final boolean ends(String s) {
        int l = s.length();
        int o = k - l + 1;
        if (o < 0)
            return false;
        for (int i = 0; i < l; i++)
            if (b[o + i] != s.charAt(i))
                return false;
        j = k - l;
        return true;
    }

    /* setto(s) sets (j+1),...k to the characters in the string s, readjusting
        k. */

    private final void setto(String s) {
        int l = s.length();
        int o = j + 1;
        for (int i = 0; i < l; i++)
            b[o + i] = s.charAt(i);
        k = j + l;
    }

    /* r(s) is used further down. */

    private final void r(String s) {
        if (m() > 0)
            setto(s);
    }

    /* step1() gets rid of plurals and -ed or -ing. e.g.

            caresses  ->  caress
            ponies    ->  poni
            ties      ->  ti
            caress    ->  caress
            cats      ->  cat

            feed      ->  feed
            agreed    ->  agree
            disabled  ->  disable

            matting   ->  mat
            mating    ->  mate
            meeting   ->  meet
            milling   ->  mill
            messing   ->  mess

            meetings  ->  meet

     */

    private final void step1() {
        if (b[k] == 's') {
            if (ends("sses"))
                k -= 2;
            else if (ends("ies"))
                setto("i");
            else if (b[k - 1] != 's')
                k--;
        }
        if (ends("eed")) {
            if (m() > 0)
                k--;
        } else if ((ends("ed") || ends("ing")) && vowelinstem()) {
            k = j;
            if (ends("at"))
                setto("ate");
            else if (ends("bl"))
                setto("ble");
            else if (ends("iz"))
                setto("ize");
            else if (doublec(k)) {
                k--;
                {
                    int ch = b[k];
                    if (ch == 'l' || ch == 's' || ch == 'z')
                        k++;
                }
            } else if (m() == 1 && cvc(k))
                setto("e");
        }
    }

    /* step2() turns terminal y to i when there is another vowel in the stem. */

    private final void step2() {
        if (ends("y") && vowelinstem())
            b[k] = 'i';
    }

    /* step3() maps double suffices to single ones. so -ization ( = -ize plus
        -ation) maps to -ize etc. note that the string before the suffix must give
        m() > 0. */

    private final void step3() {
        if (k == 0)
            return; /* For Bug 1 */
        switch (b[k - 1]) {
            case'a':
                if (ends("ational")) {
                    r("ate");
                    break;
                }
                if (ends("tional")) {
                    r("tion");
                    break;
                }
                break;
            case'c':
                if (ends("enci")) {
                    r("ence");
                    break;
                }
                if (ends("anci")) {
                    r("ance");
                    break;
                }
                break;
            case'e':
                if (ends("izer")) {
                    r("ize");
                    break;
                }
                break;
            case'l':
                if (ends("bli")) {
                    r("ble");
                    break;
                }
                if (ends("alli")) {
                    r("al");
                    break;
                }
                if (ends("entli")) {
                    r("ent");
                    break;
                }
                if (ends("eli")) {
                    r("e");
                    break;
                }
                if (ends("ousli")) {
                    r("ous");
                    break;
                }
                break;
            case'o':
                if (ends("ization")) {
                    r("ize");
                    break;
                }
                if (ends("ation")) {
                    r("ate");
                    break;
                }
                if (ends("ator")) {
                    r("ate");
                    break;
                }
                break;
            case's':
                if (ends("alism")) {
                    r("al");
                    break;
                }
                if (ends("iveness")) {
                    r("ive");
                    break;
                }
                if (ends("fulness")) {
                    r("ful");
                    break;
                }
                if (ends("ousness")) {
                    r("ous");
                    break;
                }
                break;
            case't':
                if (ends("aliti")) {
                    r("al");
                    break;
                }
                if (ends("iviti")) {
                    r("ive");
                    break;
                }
                if (ends("biliti")) {
                    r("ble");
                    break;
                }
                break;
            case'g':
                if (ends("logi")) {
                    r("log");
                    break;
                }
        }
    }

    /* step4() deals with -ic-, -full, -ness etc. similar strategy to step3. */

    private final void step4() {
        switch (b[k]) {
            case'e':
                if (ends("icate")) {
                    r("ic");
                    break;
                }
                if (ends("ative")) {
                    r("");
                    break;
                }
                if (ends("alize")) {
                    r("al");
                    break;
                }
                break;
            case'i':
                if (ends("iciti")) {
                    r("ic");
                    break;
                }
                break;
            case'l':
                if (ends("ical")) {
                    r("ic");
                    break;
                }
                if (ends("ful")) {
                    r("");
                    break;
                }
                break;
            case's':
                if (ends("ness")) {
                    r("");
                    break;
                }
                break;
        }
    }

    /* step5() takes off -ant, -ence etc., in context <c>vcvc<v>. */

    private final void step5() {
        if (k == 0)
            return; /* for Bug 1 */
        switch (b[k - 1]) {
            case'a':
                if (ends("al"))
                    break;
                return;
            case'c':
                if (ends("ance"))
                    break;
                if (ends("ence"))
                    break;
                return;
            case'e':
                if (ends("er"))
                    break;
                return;
            case'i':
                if (ends("ic"))
                    break;
                return;
            case'l':
                if (ends("able"))
                    break;
                if (ends("ible"))
                    break;
                return;
            case'n':
                if (ends("ant"))
                    break;
                if (ends("ement"))
                    break;
                if (ends("ment"))
                    break;
                /* element etc. not stripped before the m */
                if (ends("ent"))
                    break;
                return;
            case'o':
                if (ends("ion") && j >= 0 && (b[j] == 's' || b[j] == 't'))
                    break;
                /* j >= 0 fixes Bug 2 */
                if (ends("ou"))
                    break;
                return;
                /* takes care of -ous */
            case's':
                if (ends("ism"))
                    break;
                return;
            case't':
                if (ends("ate"))
                    break;
                if (ends("iti"))
                    break;
                return;
            case'u':
                if (ends("ous"))
                    break;
                return;
            case'v':
                if (ends("ive"))
                    break;
                return;
            case'z':
                if (ends("ize"))
                    break;
                return;
            default:
                return;
        }
        if (m() > 1)
            k = j;
    }

    /* step6() removes a final -e if m() > 1. */

    private final void step6() {
        j = k;
        if (b[k] == 'e') {
            int a = m();
            if (a > 1 || a == 1 && !cvc(k - 1))
                k--;
        }
        if (b[k] == 'l' && doublec(k) && m() > 1)
            k--;
    }

    /**
     * Stem the word placed into the Stemmer buffer through calls to add().
     * Returns true if the stemming process resulted in a word different
     * from the input.  You can retrieve the result with
     * getResultLength()/getResultBuffer() or toString().
     */
    public void stem() {
        k = i - 1;
        if (k > 1) {
            step1();
            step2();
            step3();
            step4();
            step5();
            step6();
        }
        i_end = k + 1;
        i = 0;
    }

    public String stem(String str) {
        reset();
        String[] parts = Pattern.compile("[_\\W+]").split(str);
        for (int zz = 0; zz < parts.length; zz++) {
            char[] word = new char[parts[zz].length()];
            parts[zz].getChars(0, parts[zz].length(), word, 0);
            add(word, word.length);
            stem();
            parts[zz] = toString();
            reset();
        }
        str = Helper.join(" ", parts);
        return str;
    } //stripAffixes

} //class
